Method and apparatus for transmitting CSI on the PUSCH in an LTE system

ABSTRACT

The present invention relates to allowing configuring CSI reporting (step S- 224, 310 ) on radio resources that are allocated over a plurality of sub frames on Physical Uplink Shared Channel (PUSCH). Allocation of said radio resources (steps S- 202, 404 ) can be performed by semi-persistent allocation or by using Transmission Time Interval (TTI) bundling. By using either semi-persistent scheduling or TTI-bundling as decided by an eNB ( 104, 204, 600 ) the UE ( 102, 202, 500 ) can be configured to report CSI (step S- 224, 310 ) for a plurality of UL transmissions. By allocating radio resources by using semi-persistent scheduling, the signaling overhead, which can be substantial for dynamic scheduling of radio resources, decreases. By using TTI-bundling the coverage of the CSI-reports increases.

TECHNICAL FIELD

The present invention relates in general to methods and arrangements ina telecommunications system, and in particular to methods andarrangements for configuring reporting of a channel state indicatorperiodically or repeatedly on a physical uplink shared channel in awireless telecommunications system.

BACKGROUND Technical Background and Existing Technology

The Long Term Evolution concept is being standardized under 3GPP. In LTEthe downlink (DL) supports channel dependent scheduling in both the timeand frequency domains, dependent on instantaneous DL channel conditions.Reference signals can for this reason be transmitted by the eNodeB basestation to the User Equipment (UE), based upon which the UE candetermine the downlink channel quality. The UEs can send Channel StateIndication (CSI) reports back to the eNodeB, which reports can beutilized by a scheduler and a link adapter located in the eNodeB, forthe allocation of resources and transmission information to the UE.

In 3GPP it has been agreed that there are two different methods oftransmitting the Channel State Indicator (CSI), periodically on thephysical uplink control channel (PUCCH), and a-periodically on thephysical on the physical uplink shared channel (PUSCH) for data orperiodically on PUSCH, see for example 3GPP TS 36.213 V8.5.0, “Physicallayer procedures”.

Different CSI formats are being used for PUCCH and PUSCH CSI reports,where the PUSCH reports comprises more frequency granular informationand therefore requires more space. The formats are typically configuredby higher layer signaling.

Through higher-layer signaling such as Radio Resource Control (RRC)signaling, the eNodeB can configure the UE to transmit CSI reportsperiodically on PUCCH. However, the size of a PUCCH CSI is very limited,in the order of 10 bits. Also, the PUCCH in LTE is used not only for CSIreports but also for scheduling requests (SRs) and Hybrid AutomaticRepeat reQuest (HARQ) ACK/NACK feedback.

The LTE uplink (UL) is based on single-carrier modulation and usesfrequency and time division multiple access principles (FDMA and TDMA).The single-carrier property of the LTE uplink makes it impossible for aUE to transmit on a physical control channel and a physical data channelin the same transmission-time-interval (TTI). Hence, if a UE istransmitting data on PUSCH and have a PUCCH CSI allocation in the sameTTI, the CSI will also be sent on the physical data channel, that is thePUSCH. In this case the smaller PUCCH format is used, althoughtransmission takes place on PUSCH. Whenever the CSI is transmitted onthe physical data channel, PUSCH, it is multiplexed with data.

However, the CSI reporting on PUSCH allows for larger CSI reports thanthe CSI reporting on PUCCH. The a-periodic CSI reporting on PUSCH meansthat the eNodeB can indicate to the UE by using a poll bit in the uplinkscheduling grant that a CSI report should be included in the uplinktransmission. The uplink grant is transmitted on the physical downlinkcontrol channel (PDCCH).

There are two mechanisms in the standard where a grant can be applied toseveral sub-frames, semi-persistent scheduling and TTI bundling.

Semi-Persistent Scheduling

Fully dynamic scheduling allows for flexibility but it also leads tohigh signaling overhead as a grant needs to be signaled in eachscheduling instance, for example for each Voice over Internet Protocol(VoIP) packet in case of VoIP. To limit the signaling load for sourceswith regular arrival rate a concept referred as semi-persistentscheduling has been agreed in 3GPP.

The underlying idea of semi-persistent scheduling is to assign resourcesusing two methods that can complement each other. Resources may forinstance partially be assigned through RRC and partially by using thePDCCH grants. For instance, the periodicity could be configured throughRRC and the actual resources and timing of the resource allocationthrough a scheduling grant on the PDCCH addressed to the UE.

The resources used for semi-persistent scheduling need to be setup atthe beginning of a connection. For VoIP, a reconfiguration of theresource should be possible at least once per talk burst in order tostart using the semi-persistent resource when the talk burst starts.There is moreover a need to revoke the semi persistent resource at theend of the talk burst to avoid collisions with dynamically scheduledresources, which may either be done explicitly or via a predefined rule,for instance that a given number of unused resources leads to revokingof the grant.

The requirement for VoIP is therefore that the resources should bereconfigured 1-2 times per talk burst, which corresponds to 1-2reconfigurations/s with a talk burst duration of 1 s.

The method how to assign resources is now agreed in 3GPP. Configurationand reconfiguration of semi-persistent radio resources is performed byusing PDCCH.

Usage of PDCCH for reconfiguring the semi-persistent resources may alsoinvolve RRC configuration setup for providing periodicity information tothe UE.

Using PDCCH can also support the usage of several resources with blinddecoding by applying the existing PDCCH format with a special RadioNetwork Temporary Identifier (RNTI). Some code points can however bereserved to decrease misdetection probability.

By using one or several additional Radio Network Temporary Identifiers(RNTIs), and letting each RNTI and its position when communicated on anout-band channel, indicate a particular scheduling method, differentscheduling methods are applicable depending on which of the RNTIs isused in the scheduling, and where the RNTI is being communicated.

TTI Bundling

Another situation where a UE may be assigned resources which are validlonger than a single sub frame is called TTI bundling or autonomousretransmissions.

The underlying idea is to improve coverage by allowing the UE toautonomously transmit several transmissions attempts without awaitingthe HARQ ACK/NACK. The purpose is either to limit the delay due towaiting for HARQ feedback or to avoid the NACK-to-ACK errors.

In 3GPP one TTI bundling concept has so far been proposed. Bytransmitting different redundancy versions consecutively it is ensuredthat the feedback response can be obtained without large HARQ Round TripTime (RTT) increase.

The configuration for TTI bundling is enabled by configuring the UE byradio resource control (RRC) for normal operation or TTI bundling. WhenTTI bundling is applied, the number of TTIs that are bundled is four.Other ways could be to use PDCCH assignment similar to what isconsidered for semi-persistent scheduling described previously.

Existing solutions for reporting CQI are periodic CQI reporting on PUCCHand a-periodic reporting on PUSCH.

For instance CSI reporting on PUCCH suffers from the low loadrequirement of PUCCH being about 20% of the capacity that thecode-division scheme is able to support. Out of 6 possible CSItransmissions per TTI, only 1-2 of those can in practice be used. Inaddition, the PUCCH channel only allows CSI reporting using smallformats that are not well suited for frequency selective channeldependent scheduling. By explicitly reporting CSI a-periodically onPUSCH, large formats that are well suited for frequency selectivechannel dependent scheduling, may be obtained. However, a-periodic CSIreporting on PUSCH may require an increased amount of radio resourceacknowledgements in the form of scheduling grant signaling on PDCCH.

SUMMARY

An object of the present invention is to provide methods and networknodes for allowing CSI reporting on Physical Uplink Shared Channel(PUSCH) with a low amount of overhead signaling, as compared to dynamicscheduling of resources.

According to an aspect of the present invention, there is provided amethod in a base station for configuring reporting Channel StatusIndicator, CSI, of a User Equipment, UE, on a Physical Uplink SharedChannel, PUSCH. This method comprises the steps of allocating uplinkradio resources spanning over at least two sub frames to the UE by usingan allocation method, providing information of the resource allocationto the UE, and providing at least an indication to the UE of a requestfor reporting CSI on PUSCH in at least one UL transmission for which theallocation is valid.

The allocation method within the method in a base station forconfiguring reporting Channel Status Indicator, may comprise allocatinguplink radio resources that are repeated periodically in time, orallocating uplink radio resources that are repeated consecutively intime.

The allocation method of uplink radio resources within the method in abase station for configuring reporting Channel Status Indicator, maycomprise semi-persistent scheduling or Transmission Time Interval, TTI,bundling.

The step of providing information of the allocation method within themethod in a base station for configuring reporting Channel StatusIndicator, may further comprise sending a UL resource grant message onthe Physical Downlink Control Channel, PDCCH.

The step of providing at least an indication of a request for reportingCSI within the method in a base station for configuring reportingChannel Status Indicator, may further comprise configuring the UE viaRadio Resource Control, RRC, indicating how CSI is to be reported.

The step of allocating uplink radio resources within the method in abase station for configuring reporting Channel Status Indicator, mayfurther comprise allocating UL radio resources in blocks of pluralconsecutive sub frames or allocating UL radio resources periodically inplural non-consecutive sub frames.

The step of reporting CSI within the method in a base station forconfiguring reporting Channel Status Indicator, may further comprisereporting an updated CSI for one of: —each semi-persistent ULtransmission of a granted periodic allocation, —a configured subset ofsemi-persistent UL transmissions of a granted periodic allocation, and—astatic subset of semi-persistent UL transmissions of a granted periodicallocation.

The step of reporting CSI within the method in a base station forconfiguring reporting Channel Status Indicator, may further compriserepeating reporting the first CSI for one of: —all transmissions, —aconfigured subset of the transmissions, and—a static subset of thetransmissions, in the case of a TTI bundling resource allocation.

The method in a base station for configuring reporting Channel StatusIndicator, may further comprise obtaining reporting CSI from the UE onthe Physical Uplink Shared Channel, PUSCH, in at least one ULtransmission for which the UL resource allocation is valid.

According to a second aspect of the present invention, there is provideda base station for configuring reporting Channel Status Indicator, CSI,related to a UE, being adapted to be connected in a telecommunicationssystem. The base station comprises a scheduling unit that is adapted toallocate UL radio resources spanning over at least two sub frames to theUE, by using an allocation method. The base station also comprises aconfiguration unit that is adapted to determine configuration of a UE toreport CSI on PUSCH, and a transceiving unit that is adapted to transmitat least an indication of the determined configuration, to the UE.

The scheduling unit of the base station may be adapted to usesemi-persistent scheduling or Transmission Time Interval, TTI bundling,for the allocation of said resources.

The configuration unit of the base station may further be adapted toconfigure the UE via Radio Resource Control, RRC. The transmitting unitof the base station may then further be adapted to transmit informationof the request for reporting CSI, wherein said information of therequest for reporting CSI indicates how CSI is to be reported by the UE.

The scheduling unit of the base station may further be adapted toschedule UL radio resources in blocks of plural consecutive sub framesor schedule UL radio resources periodically in plural non-consecutivesub frames.

According to a second aspect of the present invention, there is provideda method in a User Equipment, UE for enabling providing reportingChannel Status Indicator, CSI, on a Physical Uplink Shared Channel,PUSCH, to a base station. The method comprises the steps of obtaininginformation of a resource allocation from the base station, for whichthe radio resources span over at least two sub frames, obtaining atleast an indication of a request for reporting CSI reporti on PUSCH inat least one transmission for which the allocation is valid, andreporting CSI on PUSCH in at least one transmission for which theallocation is valid.

The method in a User Equipment, UE for enabling providing reportingChannel Status Indicator, CSI may further comprise determining the CSIof radio resources based on the request, or said at least indicationthereof, for reporting CSI.

The method in a User Equipment, UE for enabling providing reportingChannel Status Indicator, CSI may further comprise determining how toreport CSI based on the information of a resource allocation and the atleast an indication of a request for reporting CSI on PUSCH, as obtainedfrom the base station.

According to a second aspect of the present invention, there is provideda user equipment, UE for providing reporting Channel Status Indicator,CSI, on a physical uplink data channel. This UE comprises a transceivingunit adapted to receive at least an indication of a request forreporting CSI on PUSCH, and a channel status determining unit, adaptedto determine the CSI of radio resources, wherein the transceiving unitfurther is adapted to transmit a CSI report on the Physical UplinkShared Channel, PUSCH to the base station.

The transceiving unit of the user equipment, UE for providing reportingChannel Status Indicator, CSI, on a physical uplink data channel, mayfurther be adapted to receive information from the base station on howto provide CSI reporting on PUSCH.

The transceiving unit of the user equipment, UE for providing reportingChannel Status Indicator, CSI, on a physical uplink data channel, mayfurther be adapted to receive information of an allocation method fromthe base station, for which the radio resources span over at least twosub frames.

At least some of the embodiments of the present invention have theadvantage that the load on the Physical Uplink Control Channel (PUCCH)may be lowered by reporting CSI periodically on PUSCH instead ofreporting CSI periodically on PUCCH.

Similarly, the amount of grant signaling on the Physical DownlinkControl Channel (PDCCH) is reduced.

An increased coverage for PUSCH CSI reports is obtained in the case ofresource allocation through TTI bundling.

BRIEF DESCRIPTION OF DRAWINGS

In order to explain advantages and features of the present inventionherein in more detail a few embodiments will be described below, wherereferences are made to the accompanying drawings, for which

FIG. 1 illustrates communicating network nodes of a wirelesscommunication system;

FIG. 2 illustrates a basic signaling scheme according to someembodiments of the present invention;

FIGS. 3 and 4 illustrate flow-charts of method steps according to someembodiments of the present invention; and

FIGS. 5 and 6 schematically illustrate network nodes of said wirelesscommunication system.

ABBREVIATIONS

ACK Acknowledgement

ARQ Automatic Repeat reQuest

CSI Channel State Indicator

CQI Channel Quality Indicator

DL Downlink

eNB eNodeB

eNodeB Enhanced NodeB

FDMA Frequency Division Multiple Access

HARQ Hybrid ARQ

MAC Medium Access Control

NACK Negative Acknowledgement

OFDM Orthogonal Frequency Division Multiplexing

PDCCH Physical Downlink Control Channel

PMI Precoding Matrix Indicator

PUCCH Physical Uplink Control Channel

PUSCH Physical Uplink Shared Channel

RI Rank Indicator

RNTI Radio Network Temporary Identifier

RRC Radio Resource Control

SC-FDMA Single Carrier FDMA

SR Scheduling Request

TDMA Time Division Multiple Access

TTI Transmission Time Interval

UE User Equipment

UL Uplink

DETAILED DESCRIPTION

As mentioned earlier there are drawbacks with the existing ways for theUE to report CSI to the eNB base station.

One way of reducing the signaling overhead may be to configure periodicCSI reporting for PUSCH, which could be implemented by introducing novelmechanisms. However, by introducing such mechanisms the complexity forCSI reporting would increase.

Moreover, achieving a sufficient coverage for the CSI report on PUSCHcan be problematic. Without using Hybrid Automatic Repeat reQuest (HARQ)transmissions of the CSI report on PUSCH, the coverage of the CSIreports may be limited at least as often as data transmissions are senton PUSCH.

Limiting the overhead signaling for the allocation of radio resourcesfor CSI reporting may be achieved by allocating radio resources that arevalid in several sub frames.

In brief, the present invention concerns requesting reporting of CSI forUL radio resource allocations that are valid for several sub-frames.

For instance, if the UE receives an UL resource allocation that is validfor more than one sub-frame including a CSI request, a CSI report isincluded in all transmissions, a configured subset or a static subset ofall transmissions for which the allocation is valid. This means that theCSI reporting on PUSCH may be implemented using an existingsemi-persistent scheduling mechanism. In the semi-persistent allocationthe base station, that is eNodeB, may include information indicatingwhether a CSI report should be included in the semi-persistentlyscheduled transmissions or not. The semi-persistent allocation,including the CSI information, is typically revealed on PDCCH.

In semi-persistent scheduling radio resources are allocated periodicallyby allocating non-consecutive sub frames periodically in consecutiveradio frames. The CSI reporting can hence be performed periodically forPUSCH by using semi-persistent scheduling, according to some embodimentsof the present invention.

As described above, limiting the overhead signaling for the allocationof radio resources for CSI reporting can be achieved by allocating radioresources that are valid in several sub frames. Allocation of radioresources over several sub frames may alternatively be achieved by usingTTI-bundling, by which method an a-periodic reporting of CSI for PUSCHcan be provided, according to some embodiments of the present invention.

The eNB can indicate in a UL scheduling grant message weather or not aCSI should be included in all, or a configured subset of, TTI bundled ULtransmissions.

Similar to the semi-persistent allocation method as, the TTI bundlingallocation method including the CSI information may be communicated tothe UE over the PDCCH channel.

As pointed out earlier allocation of radio resources spanning overseveral sub frames has the advantage that the signaling overheaddecreases as compared to the signaling required for, for instance,dynamic resource scheduling.

In the following some embodiments of the present invention will bedescribed with reference to the accompanying figures.

FIG. 1 illustrates two network nodes of a wireless telecommunicationsystem, in the form of a UE 102 and a base station, as exemplified by anenhanced Node-B (eNB) 104, wherein said UE 102 and said base station 104are adapted to perform UL and DL transmissions, respectively.

Reference will further also be made to FIG. 2, illustrating a basicsignaling scheme for signaling between said UE 202 and eNB 204, by theuse of which some embodiments of the present invention will be describedin more detail.

One basic principle of the LTE radio access is that shared-channeltransmission is utilized, which implies that time-frequency resourcesare shared between users.

In the case the UE 202 has data to be transmitted to the eNB 204, the UE202 needs to obtain a scheduling grant that is valid before transmittingthe data to the eNB 204.

Accordingly, the UE can request radio resources by transmitting a ULscheduling resource request to the eNB. In FIG. 2 this step isillustrated in step S-210. This UL scheduling resource request istransmitted on the Physical Uplink Control Channel, PUCCH for the reasonthat this physical channel is the channel used for requesting radioresources enabling transmitting uplink data.

Having received an UL scheduling resource request by the eNB 204, saidnode may allocate radio resources over a plurality of sub frames in stepS-212, based on the received request in step S-210. As mentionedearlier, it is an advantage to allocate resources valid over a pluralityof sub frames since signaling overhead per se is decreased as comparedto allocating radio resources by dynamically scheduling the radioresources.

As mentioned above, one example of allocating radio resources overseveral sub frames is to allocate them by using semi-persistentscheduling by which non-consecutive sub frames can be allocatedperiodically. For each consecutive radio frame the radio resource isallocated periodically.

Another example of allocating resources over several sub frames is toapply Time Transmission Interval (TTI) bundling, by which consecutivesub frames are allocated a-periodically.

For both semi-persistent scheduling and TTI bundling, the resourceallocation method comprises a possibility to request for including a CSIreport in the UL transmissions for which the allocation is valid.

Dependent on the type of resource allocation the requested CSI reportmay be either a repetition of the first report or a new report. In thecase of a semi-persistent allocation a new CSI report is transmitted foreach UL transmission, or a configured subset of all. In the case of aTTI bundling allocation the first requested CSI report is repeated inall UL transmissions, or a configured subset thereof.

Having allocated radio resources valid over a plurality of sub frames instep S-212, the following step may be to determine the UE configurationfor CSI reporting in step S-213.

Thereafter the eNB 204 may transmit a UL scheduling grant to the UE 202in step S-214. According to some embodiments of the present invention,the request for reporting CSI by the UE can be comprised in the ULscheduling grant. This CSI reporting may be requested by means of achannel-state request flag included in the UL scheduling request.

In the following, a few examples of different resource allocationmethods are considered.

The UL scheduling grant may thus be communicated to the UE on thePhysical Downlink Control Channel (PDCCH). The configuration informationfor the allocation method may also be communicated on the PDCCH channel.

According to at least some embodiments of the present invention, theexisting format on PDCCH with a special Radio Network TemporaryIdentifier (RNTI) may be used.

According to some alternative embodiments wherein the RRC is used forthe allocation method, the periodic CSI reporting on PUSCH can beconfigured in two ways, a first and a second way.

In the first way, the actual multi TTI allocation is configured tocomprise the CSI. This may thus be achieved by semi-persistentlyscheduling resources on PUSCH and indicate that CSI should be includedin all semi-persistently scheduled transmissions.

In the second way, a PUCCH CSI allocation is configured to coincide withthe configured semi-persistently scheduled resource on PUSCH. By usingthe second way, a small PUCCH type of report, supported by the 3GPPstandard, or a large PUSCH type report can be sent, dependent on theconfiguration. The second way may be performed independent of anypersistent allocation methods.

As mentioned earlier, at least some embodiments of the present inventionprovide the advantage of lowering the load on the Physical UplinkControl Channel (PUCCH) and reducing the amount of grant signaling onthe Physical Downlink Control Channel (PDCCH). Moreover, in the case ofresource allocation through TTI bundling, an increased coverage forPUSCH CSI reports can also be achieved.

Returning to the signaling scheme in FIG. 2, it is illustrated in stepS-216 the step of obtaining information on the resource allocation fromthe eNB. The UE 202 can also obtain information comprising a CSIreporting request or at least an indication thereof in step S-218.

Having obtained a CSI reporting request by the UE, the actual CSI valueis now determined by the UE, which is schematically illustrated in stepS-220. Based on the determined CSI, the UE 202 may generate a CSI reportin step S-222. Having generated a CSI report by the UE, the CSI reportmay then be reported by the UE 202 to the eNB 204, in step S-224.According to some embodiments of the present invention, this may beperformed by reporting CSI on PUSCH.

The eNB can thus receive a CSI report in which the UE recommends a rankby using a Rank Indicator (RI), a Precoding Matrix Indicator (PMI) and aModulation and Coding Scheme (MCS). The eNB may then choose to eitherfollow the rank and PMI recommendations or to override them. The MCS, asindicated by a Channel Quality Indicator (CQI) is always explicitlysignaled.

In the following, method steps of both the method in a UE as well as themethod to be executed by an eNB are presented with reference alternatelyto the flowchart of FIG. 3 and to the flow-chart of FIG. 4,respectively.

The method to be executed in a UE may start by transmitting the ULscheduling resource request on PUCCH to the eNB, in step 302. Thismethod step corresponds to the signaling step S-210 of the signal schemeof FIG. 2, as presented above.

Transmitting a UL scheduling resource request by the UE in step 302 alsocorresponds to the step of receiving the UL scheduling resource requestby the eNB in step 402, as illustrated in FIG. 4.

Having received the UL scheduling resource request, the eNB may allocateradio resources that are valid over at least two sub frames in step 404.According to some embodiments of the present invention, the eNB mayallocate radio resources in step 404, which are valid over a pluralityof sub frames.

As mentioned above one example of an allocation method that allocatesradio resources spanning over at least two sub frames is thesemi-persistent scheduling method, which periodically allocatesnon-consecutive sub frames.

Similarly, as mentioned above, a second example of an allocation methodby which several sub frames can be allocated is the Transmission TimeInterval, TTI, bundling method, which allocates block of consecutivesub-frames a-periodically. TTI-bundling may be called AutonomousRetransmission.

In the case of allocating radio resources spanning over multi subframes, such as for semi-persistent scheduling method and forTTI-bundling, CSI reporting has an important role to deliver feedback tothe eNB about the DL shared channel.

Thereafter, the eNB may transmit a UL scheduling grant to the UE in step406. According to some embodiments of the present invention, this ULscheduling grant comprises the request for CSI reporting addressed tothe UE.

The UL scheduling grant including the request for CSI reporting can becommunicated to the UE on the Physical Downlink Control Channel (PDCCH).

Configuration information for the UE may be forwarded to the UE throughthe Radio Resource Control (RRC).

Returning to the flow-chart of FIG. 3 presenting method step of the UE,it is illustrated in step 304 receiving the UL scheduling grant forresources spanning over a plurality of sub frames, wherein the ULscheduling grant may comprise the request for CSI reporting.

After the UE has received the request for CSI reporting in step 304, theUE can determine the CSI in step 306. Having determined the CSI in step306, the CSI report can be prepared by the UE in step 308.

In the case of a semi-persistent scheduling or radio resourcesnon-consecutive sub frames are allocated periodically. In this case theCSI report is updated for each UL transmission or at least for aconfigured or static sub-set of the UL transmissions.

In the case of TTI-bundling allocation, the first CSI report of theblock of consecutive sub frames is repeated in all UL transmissions orat least in a configured subset of all UL transmissions.

Having prepared the CSI report in step 308, the following step may bethe step of providing the CSI reporting on PUSCH to the eNB in step 310.

In FIG. 4, presenting method steps to be executed by the eNB, step 310corresponds to step 408 of receiving CSI reporting on PUSCH.

The eNB may in this way receive information related to the quality ofthe downlink based on reference signals that can be transmitted by theeNB to the UE.

FIGS. 5 and 6 schematically illustrate network nodes in the form of a UEand an eNB base station, respectively.

According to at least some embodiments of the present invention, the UE500 in FIG. 5 comprises a channel status indicator (CSI) determiningunit 502, a CSI report preparation unit 504, and a transceiving unit506. In addition the UE 500 can also comprise a control unit 508,adapted to control said units.

The channel status indicator (CSI) determining unit 502 may be adaptedto determine the CSI of DL radio resources, such as the DL sharedchannel, based on reference symbols as transmitted by the eNB,corresponding to step 306 as illustrated in FIG. 3. The CSI reportpreparation unit 504 may be adapted to prepare the CSI report based onthe determined CSI, as comprised in step 308 of FIG. 3.

The transceiving unit 506 is typically adapted to receive the ULscheduling grant for resources spanning over a plurality of sub frames,the step of which is illustrated in FIG. 3 by step 304. The transceivingunit is further adapted to provide the CSI reporting on the PhysicalUplink Shared Channel (PUSCH), under control of the control unit 508, aspresented in step 310 in FIG. 3. In addition, the transceiving unit 506is also adapted to transmit the UL scheduling resource request, underthe control of the control unit 508, to the eNB, once the UE needs aresource allocation to transmit data to the eNB.

According to at least some embodiments of the present invention, the eNBbase station 600 as illustrated in FIG. 6 comprises a scheduling unit602, a configuration unit 604, and a transceiving unit 606. In additionthe eNB base station UE can also comprise a control unit 608, adapted tocontrol said units.

The scheduling unit 602 may be adapted to allocate UL radio resourcesspanning over at least two sub frames by using an allocation method,corresponding to the step 404 as illustrated in FIG. 4. Theconfiguration information to be transmitted to the UE for providing CSIreporting on PUSCH can be determined by the configuration unit 604,based on the resource allocation. The configuration unit 604 may betherefore adapted.

The transceiving unit 606 may be adapted to provide the determinedconfiguration, or at least an indication thereof, to the UE, bytransmitting an UL scheduling grant on Physical Downlink Control Channel(PDCCH), comprising the CSI reporting request, which is basicallyperformed in method step 406 by the eNB, as illustrated in FIG. 4. Thetransceiving unit 606 can further be adapted to receive CSI reporting onPhysical Uplink Shared Channel (PUSCH), as illustrated in FIG. 4. Inaddition, the transceiving unit 606 can also be arranged to receive theUL resource request, as presented in step 402 in FIG. 4, which requestis initially transmitted by the UE, triggered by the presence of data tobe transmitted to the eNB, and therefore the requirement of a scheduledresource allocation. Said eNB units may be controlled by the controlunit 608.

The method steps of the embodiments of the present invention mayalternatively be implemented by software executed by a processor in oneor several network nodes, such as, but not limited to, a mobile terminalalso called UE or mobile station, and/or a radio base station alsocalled NodeB or eNodeB. It should also be noted that the invention isequally applicable both in the downlink as well as the uplink of awireless system.

Means mentioned in the present description may be software means,hardware means or a combination thereof.

Any examples and terminology relating to 3GPP LTE standard being usedherein should not be seen as limiting the scope of the invention, themethodology of which in principle can be applied to other systems aswell, including for instance Wideband Code Division Multiple Access(WCDMA).

While various embodiments and variations of the present invention havebeen described above, it should be understood that they have beenpresented by way of example only, and not limitation. Thus, the breadthand scope of the present invention should not be limited by any of theabove-described embodiments. Further, unless stated, none of the aboveembodiments are mutually exclusive. Thus, the present invention mayinclude any combinations and/or integrations of the features of thevarious embodiments.

Additionally, while the methods described above are shown as a sequenceof steps in flow-charts, this was done solely for the sake ofillustration. Accordingly, it is contemplated that some steps may beadded, some steps may be omitted and the order of the steps may bere-arranged.

It must be emphasized that the present invention can be varied in manyways. The presented embodiments of the present invention are only a fewexamples of the variety of embodiments that are comprised within thepresent invention.

The following advantages can be identified of at least some of theembodiments:

It is an advantage that the load on the Physical Uplink Control Channel(PUCCH) may be lowered by reporting CSI periodically on PUSCH instead ofreporting CSI periodically on PUCCH.

Similarly, it is an advantage that the amount of grant signaling on thePhysical Downlink Control Channel (PDCCH) is reduced.

It is advantageous that an increased coverage for PUSCH CSI reports isobtained in the case of resource allocation through TTI bundling.

The invention claimed is:
 1. A method in a base station for configuringreporting Channel Status Indicator (CSI) of a User Equipment (UE) on aPhysical Uplink Shared Channel (PUSCH) comprising the steps of:allocating uplink radio resources spanning over at least two sub framesto the UE by using an allocation method; providing information of theresource allocation to the UE; and providing at least an indication tothe UE of a request for reporting CSI on the PUSCH in at least one ULtransmission for which the allocation is valid; wherein the step ofproviding at least an indication of a request for reporting CSIcomprises configuring the UE via Radio Resource Control (RRC) indicatinghow CSI is to be reported.
 2. The method according to claim 1, whereinthe allocation method comprises allocating uplink radio resources thatare repeated periodically in time, or comprises allocating uplink radioresources that are repeated consecutively in time.
 3. The methodaccording to claim 2, wherein the allocation method of uplink radioresources comprises semi-persistent scheduling or Transmission TimeInterval (TTI) bundling.
 4. The method according to claim 3, wherein thereporting CSI comprises reporting an updated CSI for one of: eachsemi-persistent UL transmission of a granted periodic allocation; aconfigured subset of semi-persistent UL transmissions of a grantedperiodic allocation; and a static subset of semi-persistent ULtransmissions of a granted periodic allocation.
 5. The method accordingto claim 3, wherein the reporting CSI comprises repeating reporting thefirst CSI for one of: all transmissions; a configured subset of thetransmissions; and a static subset of the transmissions, in the case ofa TTI bundling resource allocation.
 6. The method according to claim 1,wherein the step of providing information of the allocation methodcomprises sending a UL resource grant message on the Physical DownlinkControl Channel (PDCCH).
 7. The method according to claim 1, wherein thestep of allocating uplink radio resources further comprises allocatingUL radio resources in blocks of plural consecutive sub frames orallocating UL radio resources periodically in plural non-consecutive subframes.
 8. The method according to claim 1, further comprising obtainingreporting CSI from the UE on the PUSCH in at least one UL transmissionfor which the UL resource allocation is valid.
 9. A base station forconfiguring reporting Channel Status Indicator (CSI) related to a userequipment (UE), being adapted to be connected in a telecommunicationssystem, said base station comprising: a scheduling unit adapted toallocate uplink (UL) radio resources spanning over at least two subframes to the UE, using an allocation method; a configuration unitadapted to determine configuration of a UE to report CSI on a PhysicalUplink Shared Channel (PUSCH); and a transceiving unit adapted totransmit at least an indication of the determined configuration to theUE, wherein the indication of the determined configuration comprises arequest for reporting CSI on the PUSCH in at least one UL transmissionfor which the allocation is valid; wherein the configuration unitfurther is adapted to configure the UE via Radio Resource Control (RRC)and wherein the transmitting unit further is adapted to transmitinformation of the request for reporting CSI, wherein said informationof the request for reporting CSI indicates how CSI is to be reported bythe UE.
 10. The base station according to claim 9, wherein thescheduling unit is adapted to use semi-persistent scheduling orTransmission Time Interval (TTI) bundling, for the allocation of saidresources.
 11. The base station according to claim 9, wherein thescheduling unit further is adapted to schedule UL radio resources inblocks of plural consecutive sub frames or schedule UL radio resourcesperiodically in plural non-consecutive sub frames.
 12. A method in aUser Equipment (UE) for enabling providing reporting Channel StatusIndicator (CSI) on a Physical Uplink Shared Channel (PUSCH) to a basestation, comprising the steps of: obtaining information of a resourceallocation from the base station, for which the radio resources spanover at least two sub frames; obtaining at least an indication of arequest for reporting CSI on the PUSCH in at least one transmission forwhich the allocation is valid; and reporting CSI on the PUSCH in atleast one transmission for which the allocation is valid.
 13. The methodaccording to claim 12, further comprising determining the CSI of radioresources based on the request, or said at least indication thereof, forreporting CSI.
 14. The method according to claim 12, further comprisingdetermining how to report CSI based on the information of a resourceallocation and the at least an indication of a request for reporting CSIon the PUSCH, as obtained from the base station.
 15. A user equipment(UE) configured for providing reporting Channel Status Indicator (CSI)on a physical uplink data channel, said UE comprising: a transceivingunit adapted to receive at least an indication of a request forreporting CSI on a Physical Uplink Shared Channel (PUSCH); and a channelstatus determining unit, adapted to determine the CSI of radioresources; wherein the transceiving unit further is adapted to transmita CSI report on the PUSCH, to the base station; wherein the transceivingunit further is adapted to receive information of an allocation methodfrom the base station, for which the radio resources span over at leasttwo sub frames.
 16. The user equipment (UE) according to claim 15,wherein the transceiving unit further is adapted to receive informationfrom the base station on how to provide CSI reporting on the PUSCH.